The invention relates to a rotating anode x-ray tube according to the preamble of patent claim 1. A tube of this type is diclosed, for example, in the U.S. Pat. No. 3,229,089.
For producing high-contrast x-ray images of specimens which absorb differently for x-rays of different wavelengths, images, as is known, have been produced with rays of different wavelengths and these have then been subtracted from one another. To that end, however, the images to be subtracted from one another should be produced as close together in time as possible, i.e., simultaneously. Therefore, x-rays with different wavelengths (hardness of radiation) which were produced in one and the same radiator were employed for producing practically simultaneous x-ray images with different contrast. To that end, as mentioned, for example, in the aforementioned reference, an x-ray tube was employed which has an anode which consists of sectors with different materials. Moreover, in order to achieve x-rays which are as approximately monochromatic as possible, a filter is also provided which consists of a plurality of sectors with different material corresponding to the plurality of sectors of the anode, so that the x-rays passing through the filter receive an optimum filtration. Since the materials of the sectors of the filters are matched to those of the anode, the plates, i.e., filter and anode, must be moved synchronously relative to one another so that the allocation is retained. However, it is difficult to also maintain this allocation given the speeds of rotation standard in the operation of x-ray tubes.